Internal combustion engine piston



Jan. 31, 1961 R. H. JOHNSON 2,970,020

INTERNAL COMBUSTION ENGINE PISTON Filed Dec. 1, 1958 IN VEN TOR.

United States Patent INTERNAL COMBUSTION ENGINE PISTON Ralph H. Johnson, Dearborn, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Dec. 1, 1958, Ser. No. 777,435

4 Claims. (Cl. 309-9) This invention relates to pistons for internal combustion engines and more particularly to pistons of the type in which most of the piston is made of a substantially light material such as aluminum or an aluminum alloy having a high thermal conductivity. The piston forming the subject of the invention is particularl adapted for use in engines in which the top walls of the pistons are subject to distortion or deterioration because of direct exposure to the high temperature of the explosion which tends to soften or cause the piston top wall to flow, particularly if made of aluminum.

The main object of the present invention is to reinforce the piston head by imbedding therein a relatively coarse mesh or grating which is di-formed to the proper contour and then cast into the piston head. The screen is made of steel or other material better able to withstand the high temperature explosions at the top of the piston.

A further object of the invention is to chemically bond the screen to the piston material to reduce the danger of fatigue cracks starting at the surface of the two materials.

A further object of the invention is to use as material for such a screen a dead soft carbon steel which is relatively cheap and which has been found to satisfy the reinforcing characteristics desired for the piston head.

For a fuller understanding of the invention and the above and other objects thereof, reference may be made to the accompanying detailed description and drawing in which:

Figure 1 is a view in elevation of an internal combustion engine piston with a portion of the head broken away to illustrate the internal construction of the piston head and shows the unique reinforcing grate imbedded in the piston head.

Figure 2 is a view in perspective of the screen prior to its being imbedded in the piston head.

Referring now to the drawing, a piston 2 is shown which in the present instance is made of relatively lightweight material such as aluminum or an aluminum ice alloy having relatively high thermal conductivity. The piston 2 includes a head portion 4 and a skirt portion 6 of the same material and has imbedded therein a grate or screen 8 of relatively coarse mesh. The screen 8 preferably is of dead soft carbon steel and is chemically clean. It is die-formed to the proper contour and then cast into the piston head. While the screen 8 need not be chemically bonded to the piston material, it is desirable to reduce the danger of fatigue cracks starting at the surface of the two materials. To bond the screen, the screen is first chemically treated prior to casting.

The screen acts the same as the reinforcing steel mesh used to reinforce concrete. The screen provides a strong network of interlacings which pass from adjacent the relatively cool sides of the piston head through the hotter center area. In this way the mesh remains anchored by only a mechanical lock or else by a mechanical lock and chemical bond in the cooler or stronger ring belt area and holds the center part of the piston head in place when it becomes overheated to the degree that its own strength is no longer sufficient to resist the gaseous pressures on the piston head. The screen can be pressed into any suitable form to fit the contour of the piston head.

I claim:

1. An internal combustion engine piston comprising a head and a skirt substantially of aluminum, the head having imbedded therein a reinforcing grate of heat resistant material extending from adjacent the sides of the head through the center area thereof.

2. An internal combustion engine piston, the head and skirt of which is formed substantially of aluminum, there being imbedded in said head a piece of reinforcing steeel screen of relatively coarse mesh extending from adjacent the sides of the head through the center area thereof.

3. The structure of claim 2 in which the material of said screen is soft carbon steel.

4. The structure of claim 1 in which said grate is chemically bonded to said aluminum.

References Cited in the file of this patent UNITED STATES PATENTS 1,270,374 Buchanan June 25, 1918 1,561,081 John Nov. 10, 1925 2,057,560 Dempster Oct. 31, 1936 2,058,741 Taylor Oct. 27, 1936 2,063,904 Block Dec. 15, 1936 2,336,918 Aske Dec. 14, 1943 2,657,961 Von Lassberg Nov. 3, 1953 FOREIGN PATENTS 722,835 Germany July 22, 1942 

